#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int max(int a, int b, int c)
{
    if (a >= b && b >= c || a >= c && c >= b)
    {
        return a;
    }
    else if (b >= a && b >= c || b >= c && c >= b)
    {
        return b;
    }
    else
    {
        return c;
    }
}
int main()
{
    int a, b, c;
    scanf("%d %d %d", &a, &b, &c);
    float m = (1.0 * max(a + b, b, c)) / (max(a, b + c, c) + max(a, b, b + c));
    printf("%.2f\n", m);
    return 0;
}